Oxygen production with three operating modes, i.e. high-pressure operation, sweep-gas operation, and vacuum operation, using dense La0.6Sr0.4Co0.2Fe0.8O3-alpha (LSCF) hollow fiber membrane modules has been investigated both theoretically and experimentally. The results indicate that the vacuum operation is the best and the most economical operating mode to produce oxygen from air. The sweep-gas operation using water vapor is another choice to obtain a high capacity of oxygen production, providing that problems associated with high temperature sealing can be solved. The high-pressure operation failed to achieve the expected oxygen production capacity. For the LSCF hollow fiber membranes, the surface exchange reaction at the downstream side plays a key role in the oxygen production at operating temperatures lower than 900 degrees C (c) 2007 American Institute of Chemical Engineers.